Abrasive tool



Patented Dec. 25, 1945 so STATES PATENT OFFICE ABRASIVE TOOL Leon Nussbaum, London, England, asslgnor of one-half to Hatim Attari, London, England No Drawing. Application March 28, 1944, Serial No. 528,461. In Great Britain April 29, 1943 1 Claim.

slab made up of abrasive dust or fragments suitably bonded together mounted thereon.

Various materials have been used for the purpose of bonding together the abrasive particles or fragments but, in many instances, they have proved unsatisfactory.

According to the present invention, an improved form of tool is provided by the employment, as a bonding agent, of a material such as a metallic carbide other than the carbides of tungsten, molybdenum, titanium or cobalt, or a mixture of carbides which, in addition to possessing bonding properties, is adapted to function as a secondary abrasive or has, in some measure, abrasive properties in addition to its bonding properties.

Thus, in carrying the invention into effect there is used for the bonding agent, a relatively hard material such as a metallic carbide or mixture of carbides which is capable, in some measure, of assisting in carrying out the work to be performed by the diamond dust or other primary abrasive used. In this connection, it has been found that certain carbides, e. g., the carbides of tungsten, molybdenum, titanium and cobalt are not satisfactory or entirely satisfactory but that others are eminently suitable for the purpose in view and giveremarkably satisfactory results.

The carbide selected in any given case will be dependent upon therequirements of the finished tool. Examples of carbides which have been found suitable for use in carrying out the present invention are boron carbide, silicon carbide, zirconium carbide, nickel carbide, chromium carbide and the carbides of iron. In some instances.

agent to form an abrasive slab which is applied to or mounted on a tool carrier so that the slab becomes firmly anchored in position on the carrier. For this purpose, a slab-receiving face of the carrier is preferably formed with a plurality of keys and/Or recesses and the slab is anchored to the carrier as is described in copending application N0. 11,439/42. As is pointed out in the Specification of application No. 11,439/42, the

keys or recesses may be of any preferred form and the slab material may be applied in plastic conditions to the face of a carrier preformed with the said recesses, in such manner that the slab material is forced into the recesses before it is allowed to set and this may be effected in various ways.

According to one embodiment of the invention. a bonding agent consisting of a mixture of silicon carbide, boron carbide and aluminum oxide is used. The three ingredients are mixed in powder form, heated to a sintering temperature, cooled, crushed and graded, and the appropriate grading is subsequently admixed with the diamond dust or other abrasive to-form a mixture in which the bonding agent is not less than four times by volume the quantity of diamond present and from which the abrasive'slab is produced. In forming the rotary tool, the mixture of diamond dust and bonding agent may be placed in the lower part of a mould of circular cross section and a disc-like carrier composed of a relatively soft metal such as aluminum is placed in position thereon, the underside ofthe carrier being formed with a plurality of keyways or recesses so that the keying effect above described may ultimately be obtained. The whole is then heated to a temperature of the order of 800 C. until the metal of the carrier fuses and the mixture becomes plastic. Thereupon, the .whole is allowed to cool in a press whilst a moderate or low pressure of the order of 1 ton per square inch .or less is applied thereto.

I claim: An abrasive or cutting tool of the character however, an oxide such as boron oxide, silicon described comprising a body formed of diamond oxide, aluminum oxide or corundum may be used for the relatively hard bonding agent instead of a carbide.

In one form of the invention, the diamond dust or the like is bonded together by the bonding particles bonded together by a bond which functions as a secondary abrasive and consists of a mixture of boron carbide, silicon carbide and at least one metallic carbide.

LEON NUSBBAUM. 

